With the onset of effective antibiotic and chemotherapy of bacterial infections, viral diseases have come relatively more and more to the fore. As a consequence, tremendous efforts have been made in laboratories the world over to study these infections. The progress made in the past decade can easily be gauged by comparing the new edition of the "van Rooyen and Rhodes" with the original volume. In mere figures, 270 pages have been added and the individual page is larger than in the old edition. Many chapters had to be completely rewritten and new ones added concerning over 20 new virus diseases of man or infections only recently established as caused by viral agents.